diff --git a/tools/android/incremental_install.py b/tools/android/incremental_install.py
index bd52880..b1b91c9 100644
--- a/tools/android/incremental_install.py
+++ b/tools/android/incremental_install.py
@@ -1,3 +1,4 @@
+# pylint: disable=g-direct-third-party-import
 # pylint: disable=g-bad-file-header
 # Copyright 2015 The Bazel Authors. All rights reserved.
 #
@@ -113,6 +114,10 @@
   """Raised when the SDK on the target device is older than the app allows."""
 
 
+class EnvvarError(Exception):
+  """Raised when a required environment variable is not set."""
+
+
 hostpath = os.path
 targetpath = posixpath
 
@@ -143,6 +148,14 @@
     if self._user_home_dir:
       env["HOME"] = self._user_home_dir
 
+    # On Windows, adb requires the SystemRoot environment variable.
+    if Adb._IsHostOsWindows():
+      value = os.getenv("SYSTEMROOT")
+      if not value:
+        raise EnvvarError(("The %SYSTEMROOT% environment variable must "
+                           "be set or Adb won't work"))
+      env["SYSTEMROOT"] = value
+
     adb = subprocess.Popen(
         args,
         stdin=subprocess.PIPE,
@@ -294,6 +307,10 @@
     """Invoke 'adb shell'."""
     return self._Exec(["shell", cmd])
 
+  @staticmethod
+  def _IsHostOsWindows():
+    return os.name == "nt"
+
 
 ManifestEntry = collections.namedtuple(
     "ManifestEntry", ["input_file", "zippath", "installpath", "sha256"])